A plastic encapsulated terminal is often used in a terminal structure of lead-acid storage batteries for motorcycles.
A plastic encapsulated terminal as shown in FIG. 14 is conventionally known to the public (see Patent Literature 1). In FIG. 14, 11 denotes a terminal portion composed of a rectangular cube, 12 denotes a circular cylindrical pole portion, 13 denotes a base in the form a plate, and 14 denotes a plastic portion composed of polypropylene, polyethylene, or the like. The terminal portion 11 has a lower end integrally coupled to an upper end of the pole portion 12, and the pole portion 12 has a lower end integrally coupled to an upper end of the base 13. The terminal portion 11 has a nut insertion hole 11a bored therethrough from a side surface on the front side to a side surface on the back side in FIG. 14, and bolt insertion holes 11b and 11c bored respectively from a top surface and a left side surface toward the hole 11a. The pole portion 12 has a circular deburring flange 12a formed around its circumferential surfaces at the uppermost part, and three ribs of flanges 12b, 12c, and 12d, formed below the deburring flange 12a at intervals, each having a radius smaller than that of the deburring flange 12a. The deburring flange 12a has a circumferential surface projecting in the horizontal direction from the circumferences at the lower end of the terminal portion 11. The plastic portion 14 is formed in the surroundings of the pole portion 12 so as to wrap the deburring flange 12a and the flanges 12b, 12c, and 12d, then slightly extends outward from the upper end of the flange 12a, and rises upward so as to cover the circumferential surfaces in the lower part of the terminal portion 11 via a groove 15.
Conventionally, in the terminal portion 11 of such a plastic encapsulated terminal for lead-acid storage batteries as mentioned above, an end user inserts a rectangular cuboid nut into the nut insertion hole 11a and thereafter inserts a bolt into one of bolt insertion holes 11b and 11c formed respectively through the top surface and the left side surface, so as to allow the bolt to be threadedly engaged. Therefore, in attempts to insert the nut into a small hollow in the terminal portion, the end user may sometimes drop the nut, which has been a problem.
Further, such a nut as disclosed in Patent Literature 1 has one screw hole, and thus the bolt can be inserted into only either one of the bolt insertion holes 11b and 11c formed respectively through the top surface and the left side surface. Therefore, it has been impossible to connect an external lead wire at each of two points at the same time, and thus it has been necessary to adjust the direction of the nut each time so that the bolt insertion hole and the screw hole of the nut that are selected for connection of the external lead wire should be coincident.
Meanwhile, as a lead-acid storage battery in which a nut is pre-fixed to a terminal, an invention of “a lead-acid storage battery characterized by including: a lead-acid storage battery body; a hollow box terminal, fixed to the lead-acid storage battery body, having one surface through which a nut insertion opening is opened and at least one other surface than the one surface through which a bolt insertion through hole is opened; a nut, having outer dimensions slightly smaller than the inner dimensions of the box terminal, having an internal thread hole facing the bolt insertion through hole, and housed within the box terminal through the nut insertion opening in a posture such that the internal thread hole and the bolt insertion through hole face each other, and a nut latch provided on a cover of the lead-acid storage battery body so as to close at least part of the nut insertion opening” is publicly known (see Patent Literature 2). However, this invention has a problem of the need for separately providing a means for closing the part of the nut insertion opening to fix the nut to the terminal.
Further, Patent Literature 2 discloses, “The bolt insertion through hole 9 provided in the box terminal 4 may be provided not only through the aforementioned end surface on the front side but also through the upper surface or the back surface of the box terminal 4 in a plural number. This allows the lead wire that is connected to each of the terminal portions 3a and 3b to be attached in a plurality of directions depending on the shape of the box terminal 4, which is one type, and the direction in which the nut 6 is housed within the box terminal 4” (paragraph [0023]); however, since the nut 6 has only one internal thread hole 10, the lead wire cannot be attached thereto at each of two points at the same time, as shown in FIG. 2.
Further, a registered design of “a terminal fitting for storage batteries” (see Non Patent Literature 1) is publicly known. The article according to this design is described as: “The article according to the design of the subject application is a terminal fitting for storage batteries, which is characterized by having a configuration in which two circular through holes are provided at positions offset from each other respectively through an upper surface and a front surface of a substantially rectangular cuboid terminal portion, and a substantially U-shaped projection is provided on a bottom surface”.
Non Patent Literature 2 suggests that a nut is fixed within a hollow of such a storage battery terminal as mentioned above in which two circular through holes (holes) are provided at positions offset from each other respectively through the upper surface and the front surface of the substantially rectangular cuboid terminal portion. It reads, “In order to improve convenience and functionality of the terminal, it is made possible to attach a harness at each of two points respectively on the upper surface and the front surface of the terminal at the same time. For achieving this, a lead bushing terminal shape as shown in FIG. 3 is employed, and the positions of holes in the nut are designed to be compatible with existing batteries. Further, the terminal is designed so as to have a width larger than that of existing batteries by 3.5 mm or 4.5 mm, and the axes of the holes respectively through the upper surface and the front surface are offset from each other by 6.5 mm, so that the harness can be fixed at each of two points at the same time, as shown in FIG. 4, without the two holes intersecting each other within the terminal” (line 2 to line 11 in the right, column of page 43), and “The nut is inserted into a special lead bushing terminal that has been newly developed in order to fix the nut to the terminal in the battery production process. Thus, a technique for fixing the nut to the terminal at the time of plastic molding of the cover has been established. This prevents, in a GYZ20HL battery, the nut from falling from the terminal, even if the battery is turned over on its side so that the nut insertion opening in the terminal faces downward (see FIG. 6)” (line 6 to line 11 in the left column of page 45). However, a specific method for fixing the nut is not disclosed therein.